The present invention generally pertains to radio communication systems and is particularly directed to an improvement in radio architecture for low tier personal communication systems.
Low-tier personal communication systems utilize a variety of modulation schemes and generally use either a time-division duplex (TDD) or a frequency-division duplex communication scheme. The modulation schemes generally are either quadrature phase shift keying (QPSK) or frequency shift keying (FSK). The QPSK modulation schemes generally include .pi./4 QPSK and .pi./4 DQPSK; and the FSK modulation schemes generally include GFSK and GMSK (Gaussian minimum shift keying).
Chip sets presently used for personal communication systems include an intermediate frequency (IF) integrated circuit chip for processing a digital input signal to convert the digital input signal into an analog input signal and to provide the input signal at an intermediate frequency and for processing a received signal at the intermediate frequency to down convert the frequency thereof and to provide an output signal from the down-converted received signal; and a radio frequency (KF) integrated circuit chip for processing the input signal provided by the IF chip at the intermediate frequency to up convert the frequency thereof to a transmission frequency and for processing a received signal provided at the reception frequency to down convert the frequency thereof to the intermediate frequency. In the prior art, these chips are customized in accordance with whether the modulation scheme is QPSK or FSK and in accordance with whether the communication scheme is TDD or FDD.